import {Collection} from '../collection/Collection'
import {uuid4} from './data'

/**
 * Type structure for a single item in the global registry.
 */
export type GlobalRegistrant = { key: string | symbol, value: any }

/**
 * A convenient class to manage global variables.
 */
export class GlobalRegistry extends Collection<GlobalRegistrant> {
    constructor() {
        super()
        this.setGlobal('registry_uuid', uuid4())
    }

    /**
     * Store the given `value` associated by `key`.
     * @param key
     * @param value
     */
    public setGlobal(key: string | symbol, value: unknown): this {
        const existing = this.firstWhere('key', '=', key)
        if ( existing ) {
            existing.value = value
        } else {
            this.push({
                key,
                value,
            })
        }

        return this
    }

    /**
     * Retrieve the value of the given `key`, if it exists in the store.
     * @param key
     */
    public getGlobal(key: string | symbol): any {
        return this.firstWhere('key', '=', key)?.value
    }
}

/**
 * Export a singleton global registry for all code to share.
 *
 * Exporting an instance here guarantees that all code that import it will get the same instance.
 */
export const globalRegistry = new GlobalRegistry()